WASHINGTON—House Republican leaders, looking Wednesday for ways to ease passage of a needed increase in the federal borrowing limit this month, are considering adding sweeteners with bipartisan appeal such as a boost in pensions for military veterans.

House Speaker John Boehner (R., Ohio) has made it clear he doesn't intend to allow the government to default on its debt. But he and other GOP leaders have concluded there is no proposal to raise the debt ceiling that could pass with Republican votes alone, and they are...